Many organisms produce chemical substances that are toxic to other organisms. An important class of these compounds are medicinal antibiotics produced by yeast, fungi and bacteria, such as penicillin and streptomycin.
A major class of antibiotics is the cephalosporins. Cephalosporins, such as cephalosporin C and its derivatives, including 7-amino cephalosporanic acid, are important antibiotics. Methods of preparing cephalosporin C and its derivatives have been described, for example in U.S. Pat. No. 3,821,209; U.S. Pat. No. 3,658,649; U.S. Pat. No. 4,113,941; U.S. Pat. No. 3,776,815; U.S. Pat. No. 3,725,400; U.S. Pat. No. 4,145,539 and U.S. Pat. No. 3,960,662. However, better and more efficient methods for preparing cephalosporins are needed.